Many applications in electrical and electronic measuring circuits require the measurement of certain parameters, mathematical processing of the measurements (such as perhaps magnitude comparison), optical display of the measurement, and simultaneous recording to the measurement with suitable recording means. A typical instrument to perform all of these functions requires an analog input circuit to scale the signal to be measured, an analog to digital converter, a processor for manipulations of the digitized data, a memory to store the data, a readout with associated circuits to display the processed measurement, a digital to analog converter to record the measurement on a strip chart recorder, and perhaps a timing circuit to clear the memory after some given recording interval.
An example of a typical application is a power disturbance analyzer that monitors the power line for high voltage disturbances (spikes or impulses) which can be damaging to computers and other equipment. Such an analyzer must measure the magnitude of spikes and record the magnitude and time of occurrence, and it must have means of discriminating against lower magnitude spikes while it is in the process of recording a spike of larger magnitude that has just previously occurred. The discrimination against lower magnitude spikes is necessary because the recording process itself requires a finite period of time, and during that recording time it must be assured that the worst case measurement, i.e. the maximum amplitude, does not get erased from the memory. On the other hand, if the recorder is in the process of recording a given spike and a larger one occurs during that time, it must then instantly override the memory so that the largest magnitude is recorded.
Thus, it is advantageous to have a system for recording and displaying input data signals with a simplified system of memory stage activation with magnitude reset and discrimination that provides a direct, lighted display from the memory, of the meter readings.